Question

Which one of the following groups of three animals is correctly matched with their one characteristic morphological feature?

Sl.No	Animals	Morphological feature
1.	Scorpion, spider, cockroach	Ventral solid central nervous system
2.	Cockroach, locust, Taenia	Metameric segmentation
3.	Liver fluke, sea anemone, sea cucumber	Bilateral symmetry
4.	Centipede, prawn, sea urchin	Jointed appendages

Answer 1

Hint: Morphological feature refers to the general aspects of biological form and arrangement of the parts of a plant or an animal.

Complete answer:
Let us analyse each given option to find out the correct answer.
- Scorpion, spider, and cockroach are invertebrates and belong to the Phylum Arthropoda, therefore they have a ventral solid central nervous system. Thus, this is correctly matched.

- In Taenia, the body is without true segments. The term segmentation refers to the feature of the body plans of a number of diverse animal groupings, including the annelids, arthropods, and chordates. In Taenia, the body is without true segments. Taenia is a genus of tapeworm and belongs to the phylum Platyhelminthes. The characteristics feature of this phylum include a flat body, the body is also not segmented and they do not have specialized systems and do not have any cavity. In cockroaches and locusts, the body is segmented externally. Thus, this morphological feature does not match correctly with the groups of three animals.

- Bilateral symmetry refers to the symmetrical arrangement of an organism or a body part, along a central axis, so that the body is divided into equivalent right and left halves by only one plane. Liver fluke has bilateral symmetry, sea anemone has radial symmetry and sea-cucumber has bilateral symmetry in larval form and radial symmetry in adult form. Thus, this morphological feature does not match correctly with the groups of three animals.

- Centipede and prawn have jointed appendages as they belong to the phylum Arthropoda while sea urchin does not have jointed appendages. Sea urchin is a spiny marine invertebrate animal belonging to the phylum Echinodermata) with a globular body. Thus, this morphological feature does not match correctly with the groups of three animals.

Hence the correct answer is option A.

Note: The ventral nerve cord consists of the subesophageal ganglion in the head, connected to the brain by circumesophageal connectives, and a chain of ganglia in the thoracic and abdominal segments interconnected by paired nerves.